contents. In particular, it does not check the values against the set of
valid values but serves whatever you pass it.
+* guid
+
+ Specifies a globally unique ID for a page. This guid will be used,
+ rather than the page url, to identify the page in RSS and Atom feeds.
+
+ The guid can either be a uuid (ie,
+ "ec248d04-f347-4eb8-92b6-671b15d36980"), or it can be an alternative URL
+ for the page.
+
+ This is mostly useful when a page's feed has moved, to keep the guids for
+ pages unchanged and
+ [[avoid_flooding_aggregators|howto_avoid_flooding_aggregators]].
+
If the field is not one of the above predefined fields, the metadata will be
written to the generated html page as a <meta> header. However, this
won't be allowed if the [[htmlscrubber]] is enabled, since it can be used to